1. Technical Field
The present invention relates to orthopedic surgery and in particular to devices for stabilizing and fixing the bones and joints of the body. Particularly, the present invention relates to a dual action instrument capable of reducing a rod into position in a rod receiving notch in the head of a bone screw with a first action and subsequently locking the rod into that receiving notch by a second action of the same instrument.
2. Background Art
The spinal column is a complex system of bones and connective tissues that provides support for the human body and protection for the spinal cord and nerves. The human spine is comprised of thirty-three vertebrae at birth and twenty-four as a mature adult. Between each pair of vertebrae is an intervertebral disc, which maintains the space between adjacent vertebrae and acts as a cushion under compressive, bending and rotational loads and motions.
There are various disorders, diseases and types of injury, which the spinal column may experience in a lifetime. The problems may include but are not limited to scoliosis, kyphosis, excessive lordosis, spondylolisthesis, slipped or ruptured disc, degenerative disc disease, vertebral body fracture, and tumors. Persons suffering from any of the above conditions typically experience extreme or debilitating pain and often times diminished nerve function.
One of the more common solutions to any of the above mentioned conditions involves a surgical procedure known as spinal fusion. A spinal fusion procedure involves fusing two or more vertebral bodies in order to eliminate motion at the intervertebral disc or joint. To achieve this, natural or artificial bone, along with a spacing device, replaces part or all of the intervertebral disc to form a rigid column of bone, which is stabilized by mechanical hardware.
The mechanical hardware used to immobilize the spinal column typically involves a series of bone screws and metal rods or plates. When the spine surgery is posteriorly performed, it is common practice to place bone screws into the vertebral bodies and then connect a metal rod between adjacent vertebral bodies. When the spine surgery is performed anteriorly, it is common practice to attach a thin metal plate directly to the vertebral bodies and secure it to each vertebral level using one or more bone screws.
The process of properly inserting the spinal rod into the receiving slot of a bone screw and then securing that connecting rod in place often can require that the surgeon use a number of instruments and expend a great deal of time and effort to accomplish the task. When bone screws in several adjacent vertebrae are to be securely connected by a spinal rod, the repeated process of inserting the rod into the heads of the one screws and then securing the rod in place for each respective bone screw can be difficult, tiresome and time consuming. It is therefore important that an instrument be provided that is specifically designed to facilitate the process for the surgeon such that the connecting rod can be easily and quickly inserted into each bone screw and with minimal effort and loss of time. It is also desirable that the rod be secured into position in the bone screw head without the application of additional torsional force to the bone screw and the bone into which it is attached.
Conventional efforts to meet this need have fallen short in that no single instrument has been provided that effectively positions and inserts a connecting rod into position in the receiving slot of the head of a bone screw and also provides a torque-free locking action to secure the rod in place.
For these reasons there remains a need for a device which, can with a single action first securely grasp the head of a bone screw and accomplish the reduction of a posteriorly introduced rod into the head of that bone screw and in a second simple action provide a torque-free locking process of the rod into the bone screw head.